Elevator control system



June 29, 1937. H. w. WILLIAMS 7 ELEVATOR CONTROL SYSTEM 3 Sheets Sheet 1 Filed May 8, 1955 I N V E N TO R fiara/c/h/ h fl/fams ATT EY 4 Y B Il o c o a 4 n u w a W Z Wu 3 F u 3 o 1| F 5 H u 5 a n 3 A I n n M n W June 29;, 1937. H. w. WILLIAMS ELEVATOR CONTROL SYSTEM Filed May 8, 1955 3 Sheets-Sheet 2 1N ,2 w M at 4 u p w 4 5 6 m3 W s Nk\- %\k\ \%\Q\\ 0 2 W M a S !fi .I Illl WW1 A/r g a 9 a w g 1M N D D P 6 m Wm 6 5 4 7 W 4 Z. a @M M %w G g Q" p f Q Q m1 2 2 2 r 1 z p p p 4 m 6 6 Lb flu M H 0 m AW e z a 1 W 0 a 4 4 WWW Ill 9 7. F M F a F a mi 0 M 6 5 W w W o C W 39 a A 4 u a AF 1 n n 5 3 w M p E 0 w 5 3 p p p i 4 M Y 4 ii i i l N VENTOR Haro/dMM/flbma.

; WITNESSES:

ATT NEY June' 29, 1937. H. w. WILLIAMS ELEVATOR CONTROL SYSTEM Filed May 8, 1955 5 Sheets-Sheet 3 e W W Mum llllllllllllllllllll 2 (i w m m 5 M ium at 2m 0 mlw AW m w W W M m 6 e D e 1 lllllll|ll|liizlk- La w v Rm 5 m w m a 7 QQ Z v 3 4 U b mg lvmv wapw F M Q AZIIIq? WITNESSES:

6Z4 f M ATT EY Patented June 29, 1937 PEN? FFHQE ELEVATOR CONTROL SYSTEM Application May 8, 1935, Serial No. 20,363

14 Claims.

My invention relates, generally, to electric elevator systems, and it has particular relation to control systems therefor.

It is customary to provide an elevator car with a car door assembly in some form, in order to protect the passengers while the car is being operated in the hatchway. Each floor is also provided with a floor door assembly which is ar ranged to be opened to permit passengers to enter and leave the car. In order to operate each of the door assemblies, an electric motor is operatively connected to each of them through an appropriate operating mechanism, so that on energization the door assemblies may be opened or closed, as the case may be.

When the elevator car stops at a floor, the motor of the floor door assembly is energized simultaneously with the energization of the motor which is connected to the car door assembly. The door assemblies are then operated simultaneously for either opening or closing. The motors are arranged to be connected in parallel circuit relation to a source of electric power and may be initiated in operation either automatically, as soon as the elevator car reaches a predetermined position in the hatchway, or in response to the operation of a manual control switch. The motors may be energized to close the door assemblies either in response to the operation of a manual control switch, or in response to auxiliary contact members located on the master control switch.

The particular floor door assembly that is operated, ordinarily, depends upon the presence of the elevator car at the floor. That is, control circuits are provided individual to each floor to selectively operate the floor door assembly at the floor where the elevator car is stopped. It is, of course, intended that the control circuit shall be completed only if the car is present at the floor.

There is the possibility, however, that the control circuit may be maintained in the operated condition after the elevator car leaves the floor. This faulty operation may be caused by a relay or relays failing to return to the non-operated condition, to relay contact members sticking in the closed position, faulty insulation, or any other condition which might be effective to disturb the intended operation of the system. If such a condition occurs, then, on the operation of the floor and car door assemblies at the next floor, the floor door assembly at the floor which has just been left by the car will also be opened, This operation is caused by the circuit arrangement in which the floor door assembly motors are arranged to be connected in parallel circuit relation with the car door assembly motor. Not only will the floor door assembly be opened at the floor where the car has stopped, but also the floor door assembly will be opened at the floor where the control circuits have failed to be restored to their non-operated condition.

This condition presents the hazard that a floor door assembly may be opened when the car is not present at the floor. There is then the ever present possibility in such an event that a person may inadvertently fall down the elevator shaft, since it is the normal reaction to pass through the opening ordinarily closed by the floor door assembly when it is opened. This result is likely to happen when the passenger does not notice that the elevator car is not present at the floor, although the floor door assembly is in the open condition.

It is, therefore, an object of my invention to provide an elevator control system which shall be simple, safe and efiicient in operation, and which may be readily and economically manufactured and installed.

The principal object of my invention is to prevent the opening of a floor door assembly of an elevator system when the elevator car is not present at the floor.

An important object of my invention is to prevent the automatic opening of any of the floor door assemblies of an elevator system on the happening of a condition which would cause a floor door assembly to be opened when the elevator car is not present at the floor.

Another object of my invention is to provide for disconnecting from a power source the control circuits for energizing the floor door operating motors of an elevator system in the event that one of the motors would be energized at a floor where the elevator car is not present on the energization of the motor at the floor where the car is actually located.

Still another object of my invention is to provide a protective relay for disconnecting from a power source, by blowing fuses or otherwise, the control circuits for energizing the floor door operating motors of an elevator system in the event that the control circuits individual to a motor at a floor which has been left by the car remain in the operated condition, thereby making impossible the opening of a fioor door at a floor where the elevator car is not present.

Other objects of my invention will, in part, be obvious, and in part, appear hereinafter.

My invention is, accordingly, disclosed in the embodiment hereof illustrated in the accompanying drawings, and comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description, taken in connection with the accompanying drawings, in which:

Figure 1 is a view, partly in side elevation and partly in section, showing the arrangement of an elevator car in the hatchway;

Fig. 2 is a diagrammatic View showing the circuit connections which may be employed in practicing my invention; and

Fig. 3 is a view showing the relative arrangement of certain of the contact members: and operating windings illustrated in Fig. 2.

In practicing my invention, I provide an elevator car which is operable in a hatchway. The operating mechanism for the elevator car may comprise a variable voltage control system, together with suitable control circuits and apparatus for starting and stopping the elevator car at the will of the operator or passengers, to permit passengers to enter and leave the car at the various floors.

In order to permit entrance to and exit from the elevator car, a floor door assembly is provided. at each floor and the elevator car itself is provided with a car door assembly. Each of these door assemblies is provided with an electric motor which, when energized, is adapted to open or close the door assembly associated therewith. A control motor is also provided, which serves to control the time of energization of the motors individual to the door assemblies, so that after they are fully opened or fully closed, the door motors will be deenergized. A system in which this means of door control is provided is illustrated in Patent No. 1,966,233 to Carney, patented July ii), 193% and assigned to' the assignee of this application. As set forth in the patent to Carney, the control motor and the motor individual to the car door assembly are arranged to be operated in parallel circuit relation with the motor which is individual to the floor door assembly at the floor where the elevator car is stopped.

In order to control the operation of the motor individual to the floor door assembly at the floor where the car is stopped, a switch is provided at each floor (in this embodiment of the invention a switch of the inductor type) which is arranged to be operated normally only when the elevator car is at a floor. When the elevator car arrives at a floor circuits. may be automatically completed for connecting the three motors in parallel circuit relation to open. the door assemblies. The motors may be initiated in operation automatically as soon as the elevator car arrives at a predetermined point in relation to the floor, or they may be initiated in operation manually by the operator after the car has arrived at the floor. After the passengers have either entered or left the car, the door assemblies may be closed either by manually operating a control switch, or auxiliary contact members may be provided on the car master control switch. As soon as the door assemblies are closed, circuits are then completed which will permit the elevator car to be moved away from the floor.

In the event that the iloor inductor switch which serves to complete the connections for the floor door motor at the floor just left by the elevator car should remain in the operated condition, then on the energization of the motors at the next floor where the elevator car stops, the motor at the previous: floor will also be energized. As a result, there will be two floor door assemblies that are simultaneously operated; the one where the car is located, and the other at the floor from which the car has just departed. There is then the possibility, as set forth hereinbefore, that a person may enter the elevator hatchway through the open door assembly where the car is not located, and as a result he may be either seriously injured or killed.

In order to prevent the false operation of a. floor door assembly, a floor door protective relay is provided. This relay is arranged to be energized after the elevator car leaves a floor only in the event that the control circuits for the motor individual to the fioor door assembly are not restored to the non-operated condition after the car leaves the floor. In the event that the normal operation does not take place and the control circuits are not restored to the normal condition, then the door protective relay is energized.

In this modification of the invention, the door protective relay is provided with contact members which are arranged to short circuit the con ductors connecting the door operating motors to the power source. Protective fuses are interposed between the conductors and the power source and as a result, when the short circuit occurs, they are immediately blown. It is thus impossible to energize any of the car door motors until the operator replaces the blown fuses. The fact that the fuses have blown indicates that there is a faulty operation in the functioning of the control circuits for the floor door motors and an inspection can. be made to clear the fault.

It is, of course, possible to arrange the door protective relay so that itwould open the circuit to the door motors by operating a relay of the latching type. Also, a circuit breaker of the thermal overload type could be employed. However, these modifications require further apparatus which may get out of order and they add complications to the system. The simplest and safest protective means for insuring that a floor door assembly will not be opened when the elevator car is not present at the floor appears to be in the use of the protective fuses. Since they will be blown only rarely because of faulty operation of the system, it is also clear that they are the most economical in use.

Referring now particularly to Figs. 1 and 2 of the drawings, it will be observed that an elevator car i ii is provided for operation in a hatchway. The elevator car it) may be supported by means of a cable H which is passed over sheaves i2 and it to a suitable counterweight I l. The sheave i2 is mounted on a shaft l5, which is arranged to be driven by means of a motor, shown generally at H5. The motor [6 is'provided with an armature ii and a motor field winding H8. The motor it may be energized by means of a generator, shown generally at l9, which is provided with an armature 2t and a separately excited main field winding 2i. As illustrated, the armatures ll and 20 are connected in loop circuit relation and provision is made for controlling and reversing the excitation of the generator field winding 2E, as is the customary practice in variable voltage elevator systems.

In order to stop the elevator car at a floor after the motor I 6 has been deenergized, a brake, shown generally at 22, is provided. The brake 22 includes a brake shoe 23, which is arranged to engage a drum 2 mounted on the shaft l5. The brake 22 may be released by means of a brake operating winding 22w.

In order to protect the passengers in the elevator car l 6 while it is being operated in the hatchway, a car door assembly, shown generally at 25, is provided. This assembly comprises doors 2E and 27, which may be operated through an interconnecting lever mechanism 28 and a reduction gearing mechanism 29 by means of a car door motor CDM, having a field winding CDF and an armature CDA.

At each floor a floor door assembly, shown genorally at 33, is provided. This assembly comprises doors 33 and 35 which may be operated through an interconnecting lever mechanism 36 by means of motors which are individual to each floor. Thus, for the fifth floor, a door motor 5D is provided. Similarly, for the fourth and sixth floors, door motors 5D and 6D are respectively provided. The door motors individual to each floor are provided respectively with field windings dDF, 5DF, GDP and armatures 4DA, EDA, EDA.

In order to energize the door motor individual to a floor, a door inductor DI carried by the car, is provided. The door inductor DI is arranged to be energized when the elevator car ll] arrives at a floor. Its energization causes the completion of control circuits to energize the fioor door motor individual to the particular fioor where the elevator car Ill is located. For example, at the sixth floor, when the door inductor DI is energized contact members BDIl and BDIZ are bridged. Similarly, at the fifth fioor, under like conditions, contact members 5DII and 5DI2 are bridged, while at the fourth floor, under like conditions, contact members lDIl and 41312 are bridged. he circuit connections which are completed as a result of these contact members being bridged will be set forth in detail hereinafter. In View of the fact that the invention may be practiced in connection with an elevator system operating past any number of floors, only three floors have been illustrated. It will be understood, however, that the system may be extended to include as many floors as are desired.

In order to disconnect the car door motor CDM and the fioor door motor individual to the fioor where the car is stopped from the power source when the door assemblies individual thereto have been opened, or closed, to the desired extent, a control motor CM is provided. This motor is provided with a field winding CF and an armature CA, and is arranged to operate a door limit switch DL, which contains contact members DL! and DL2. Contact members DLl are normally closed when the door assemblies are closed. When they are operated to the full open position contact members DLl are opened and contact members DL2 are closed. The latter contact members remain in the closed position until the door assemblies have been closed to the desired extent. At this time, they are opened and contact members DLl are again closed.

The car door motor CDM, the control motor CM and the motors individual to the door operating assemblies at each floor are of the series type. A reversal in the direction of their operation is obtained by reversing the connections to the armatures, the connections to the field Windings remaining the same.

In order to start the elevator car l0, an up reversing switch U is provided for operating the car l8 in the up direction, and a down reversing switch D is provided for operating the elevator car H) in the down direction. The reversing switches are arranged to be selectively energized by means of a master switch MS. Thus, when the handle of the master switch MS is operated to the right, a circuit is completed through contact member MSD to energize the operating winding of the down reversing switch D through the operating winding of a control relay CR. In like manner, when the handle of the master switch MS is operated to the left, a circuit is completed through contact member MSU to energize the operating winding of the up reversing switch U through the operating winding of the control relay CR. Shortly after the elevator car is started in either direction, a speed switch V is energized which is arranged at contact members VI, to short circuit a resistor 46 for the purpose of applying full excitation to the separately excited main field winding 2! of the generator I 9.

In this modification of the invention, the elevator car I0 is stopped at a floor by centering the master switch MS. The operating winding of a slowdown inductor switch E is then energized. The slowdown inductor switch E may be carried underneath the elevator car l0 and is provided with normally closed contact members El and E2. slowdown inductor switch E is energized and the contact members El are moved into proximity with an inductor plate SEU, for example, they will be opened. In like manner, when the elevator car It] is moved in the down direction the contact members E2 are moved into proximity with inductor plate GED, for example, they will be opened. The contact members El and E2 are connected, respectively, in the up and down circuits for energizing the operating winding of the speed switch V. As: a result, the opening of either of these contact members efiects the deenergization of the speed switch V and causes the resistor 46 to be reinserted in series circuit relation with the separately excited main "1:.

field winding 2|.

It will be apparent that the elevator car Ill may also be arranged to be stopped in response to a hall call which is registered by a passenger at a floor. However, since the apparatus and method of control of the movement of the elevator car forms no part of this invention, only the simplest form of car control is illustrated and described herein.

In order to finally stop the elevator car H] at a floor, a landing inductor switch F is also provided and it may also be carried underneath the elevator car it. The landing inductor switch F is provided with normally closed contact members El and F2, which are arranged to be opened When they are respectively moved into proximity with inductor plates SFU and GED, for example, when the operating winding of the landing inductor switch F is energized, and depending upon the direction of movement of the elevator car lfi. The contact members FI and F2 are connected in the energizing circuits to the up and down. reversing switches U and D, respectively. When they are opened, the operating windings: of the reversing switches are deenergized, the main field When the operating winding of the winding 2| of the generator I9 is deenergized and the brake 22 is applied.

In order to open the car door assembly 25 and any of the floor door assemblies 33, a door opening relay DOR is provided. As set forth hereinbefore, this relay may be energized automatically upon the arrival of the elevator car ill at the floor, or it may be energized in response to the operation of a control switch, for example the control switch CS, to effect its operation. The door assemblies may be closed in response to the operation of a door closing relay DCR. The operating winding of this relay may be energized by means of the control switch CS or auxiliary contact members may be provided, as set forth hereinbefore, on the master switch MS to effect its energization.

With a view to preventing a false operation of any of the floor door assemblies 33, a door protective relay DPR is provided. The operating winding of this relay is arranged to be connected as illustrated in series circuit relation with any of the field windings iDF, EDF, or fiDF of the floor door motors 5D, 5D or 61), respectively. The energizing circuit to the door protective relays DPR. is arranged to be maintained in the open condition by means of contact members SR! of a speed relay, shown generally at SR, in Fig. 1 of the drawings. Contact members Vl of the speed switch V are also provided in series circuit relation with the operating winding of the door protective relay DPR for a purpose which will be set forth hereinafter.

The speed relay SR may comprise a fly-ball governor mechanism having balls til which are arranged to be rotated by means of a shaft 32, having at the lower end thereof a bevel gear wheel 43 that is arnanged to engage a corresponding bevel gear wheel 44 that is mounted on the shaft l5. An arm .5, carried by the operating mechanism of the speed relay SR, is arranged to close contact members SRl when the shaft I5 is driven above a predetermined. speed.

The door protective relay DPR is provided with contact members DPRl, which are arranged when closed, to short circuit conductors L3 and L4. As illustrated, conductors L3 and L l are connected through protective fuses 50 and Bi, respectively, to conductors Li and L2, which in turn, may be connected to a suitable source of direct current. Thus, if conditions exist which, as will be set forth hereinafter, are such as to cause the energization of the operating winding of the door protective relay DPR, then contact members DPRi will short circuit the conductors L3 and L l, which serve to energize the various door operating motors and as a result, the protective fuses 56 and 5! will be blown. It will then be impossible to energize the door operating motors until the fuses 5t and El have been replaced.

In describing the operation of the foregoing system, it will be assumed that the conductors L! and L2 are connected to a suitable source of 'rect current. It will also be assumed that the generator I!) is driven at a suitable speed by means of a suitable driving mechanism.

The operator operates the handle of the master switch MS to the left to complete a circuit for energizing the operating winding of up reversing switch U and the operating winding of the control relay CR. This circuit may be traced as follows:

Ll, MS, MSU, Fl, U, CR, door interlocks, L2

At contact members U5, a holding circuit is completed for the operating windings of the switch U and the control relay CE. The separately excited main field winding 2! of the generator I9 is energized over a circuit which may be traced as follows:

LI, U2, 2!, U3, 40, L2

The brake 22 is released on the energization of the brake releasing winding 22w over a circuit which may be traced as follows:

Ll, 22w, Ul, L2

The elevator car I is now operating in the up direction at reduced speed.

In order to operate the elevator car at full speed, the speed switch V is energized. The circuit for energizing this switch may be traced as follows:

Ll, U5, El, V, L2

The elevator car ii] is now operating at full speed in the up direction.

It will be assumed that it is desired to stop the elevator car at the fifth floor. The operator will then center the master switch MS and as a result, a circuit will be completed for energizing the holding relay HR.

S, HR, CR5, L2

At contact members HR! a self-holding circuit is completed for the operating winding of the holding relay HR. It will be observed that the operating winding of the slow-down inductor switch E is energized in parallel circuit relation with the operating winding of the holding relay HR. When the contact members El of the slowdown inductor switch E are moved into proximity with the inductor plate EEU, they are opened and the previously traced energizing circuit for the operating winding of the speed switch V is opened. The resistor 49 is then again inserted in series circuit relation with the main field winding 2i of the generator l9, and the speed of the elevator car NJ is correspondingly reduced.

The deenergization of the operating winding of the speed switch V causes contact members V2 to be closed. Contact members V3, however, are retarded in opening because of a dashpot 52,

which permits the opening of these contact members only after the expiration of a predetermined time interval and for a purpose which will be set forth hereinafter. The return of the speed switch V to the non-operated position also closes contact members Vi for energizing the operating winding of the landing inductor switch F, and contact members V which completes an obvious energizing circuit for the operating winding of the door inductor switch DI. Also after the expiration of a predetermined time caused by a dashpot 53, contact members VG are closed and a circuit for energizing the operating winding of the door opening relay DOR is completed.

L3, CSE, DOR, DLI, V6, L4

The door assemblies 25 and 33 are then caused to be opened while the elevator car II! is still approaching the fifth floor. Due to the fact that there is a time delay in the opening of the contact members V3, a shunt circuit will be momentarily maintained around the door interlocks, so that the up reversing switch U may still be energized for a suificiently long time to permit the elevator car it to be brought to the floor level.

Since the operating winding of the door inductor switch DI is energized, contact members EDI! and SD12 will be bridged. In addition, since the door opening relay DOR is now also in the operated position, circuits are completed for energizing the car door motor CDM, the control motor CM and the floor door motor 5D at the fifth floor. The circuits for energizing these motors may be, respectively, traced as follows:

L3, CDF, DORI, CDA, DDR3, L4?

L3, CF, DORI, CA, DORS, L4

L3, 5DII, 5DF, DDR2, DORI,

5DA, 5DI2, DORS, L4

While the door assemblies 25 and 33 are being opened, the contact members F! of the landing inductor switch F are moved into proximity with the inductor plate 5FU. Since the operating winding of the landing inductor switch F is energized, contact members Fl will be opened and the previously traced energizing circuit for the operating windings of the up reversing switch U and the control relay CR will be opened. This switch and relay will then be deenergized. As a result of the deenergization of the up reversing switch U, the previously traced energizing circuit for the main field winding 2i of the generator i9 is opened. In addition, the energizing circuit for the brake releasing winding 22w is opened and the brake 22 is applied to stop the elevator car it at the fifth floor.

Meanwhile, the door assemblies 25 and 33 are being opened. The motors will remain in the energized condition until the door limit switch DL is operated by the control motor CM to open contact members DL!. The previously traced energizing circuit for the operating winding of the door operating relay DOR is then opened and it is deenergized. The motors then are deenergized and no further action takes place until a subsequent operation is initiated by the operator.

After the passengers have entered or left the elevator car it at the fifth floor, the door assemblies 25 and 33 may be closed by the operation of the control switch CS. In response to the operation of this control switch, a circuit is completed for energizing the operating winding of the door closing relay DCR, which may be traced as follows:

L3, CS2, DCR, DLZ, L4

cuits for energizing the motors CDM, CM and 5D for closing the door assemblies 25 and 33 may be traced, respectively, as follows:

L3, CDF, DCRI, CDA, DCRS, L4

L3, CF, DCRI, CA, DCR3 L3, 'EDII, EDF, DCRZ, DCRI, 5DI2, 5DA, DCR3, L4

The motors continue to operate until the control motor CM operates the door limit switch DL to open contact members DL2. The previously traced energizing circuit for the operating winding of the door closing relay DCR is then opened. This'relay is deenergized and the various motors are deenergized. The operator maintains the control switch CS in the operated position until after the elevator car It has left the floor, in order to prevent the automatic opening of the doors until the speed switch V is operated to open the contact members Vt. As set forth hereinbefore, it will be obvious that the function of the control switch CS may be incorporated in the operation of the master switch MS. However, for the purposes of simplicity in illustrating the invention, the control switch CS is provided.

The operator then may move the handle of the master switch MS to the left to again initiate the operation of the elevator car it in the up direction. Since the s quence of starting the elevator car i3 is same as that set forth hereinbefore, it will not be repeated.

further result of the operation of the speed switch V is to open contact members V5, thereby deener-gizing the operating winding of the door inductor switch DI. The deenergization of this winding, as well as the movement or" the door inductor, out of proximity with the operating mechanism associated with the contact members EDI! and EDIE, causes them to be restored to the non-operated condition in which these contact members are not bridged.

It will now be assumed that the elevator car it? is to be stopped at the sixth floor. The foregoing described sequence of operation will take place in stopping the car at this floor. As soon as the contact members V6 are closed after the expiration of the time controlled by the dashpot 53 has elapsed, the door opening relay DOR will automatically be energized to initiate the opening of the car door assembly 25 and the floor door assembly 33 which is associated with the sixth floor.

As has been set forth hereinbefore, there is the possibility that the contact members of the door inductor switch at a preceding floor, for example, the fifth floor, and contact members EDI! and SDIZ, may, for some reason or other, remain in the closed or operated position. Under this condition, the fifth floor door motor 5D will be energized in parallel circuit relation with the sixth floor door motor 6D. As a result, the door assembly 33 at the fifth floor will be opened at the same time that the corresponding door assembly at the sixth floor is opened.

It is in order to prevent the possibility of this false operation taking place that the door protective relay DPR and the speed relay SR are provided. As soon as the elevator reaches a predetermined speed, the contact members SRI of the speed relay SR are bridged and they remain in this condition while the elevator car is running and until the speed thereof is reduced to the predetermined speed. Under normal operating conditions the contact members SR! are opened before contact members DOR2 are closed because of the time delay in the closing of contact members V5. There is thus ordinarily no possibility that an energizing circuit for the operating winding of the door protective relay DPR will be completed through the series field windings CDF and CF. Furthermore, the contact members SR8 are opened before the contact members of the door inductor DI are normally bridged.

In the event that the contact members SDI! should remain in the bridged condition at a time when they should in the normal operation of the system, be opened, then a circuit is completed for energizing the operating winding of the door protective relay DPR, as soon as the speed switch V is deenergized, preparatory to stopping the elevator car H) at the next floor. traced as follows:

L3, EDII, 5DF, DPR, SR V1, CR2, L4

Ihe operation of the door protective relay DPR causes contact members DPR,! to be bridged, and as a result, a direct short circuit is applied by the conductors L3 and L4. One or both of the protective fuses 50 or 5! will be blown as a result of this short circuit. It is then impossible to automatically energize any of the door operating motors until the fuses that have been blown have been replaced.

When the operator arrives at a floor and finds that the doors do not open automatically, he can then open them manually at the particular This circuit may be floor where the car is located, and he can inform the maintenance man that a faulty operation has taken place. An investigation can be made to determine the cause of the trouble.

It will, therefore, be observed that it is impossible to obtain a faulty operation of the door operating mechanisms when the protective system set forth hereinbeiore is provided in an elevator system. As soon as it is attempted to open the doors at a particular floor, and conditions exist which would cause the doors at another floor to simultaneously be opened, then it is not possible to open any of the doors. As a result, a hazard is removed from the operation of an elevator system which would otherwise be present.

Since certain further changes may be made in the foregoing construction and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter set forth in the foregoing description or shown in the accompanying drawings shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. In an elevator system in which an elevator car is operated past a plurality of floors, each floor having a door assembly, in combination. operating means individual to each door assembly and disposed to open it to permit entrance .to the elevator car at the floor, control means for selectively energizing the operating means individual to the floor where the elevator car is stopped, and protective circuit means disposed to be rendered effective during a predetermined portion of the travel of the elevator car from said floor and ineffective during the remaining portion of its travel for preventing the energization of any of said operating means in the event that said control means remains in the operated condition after the elevator car leaves said floor.

2. In an elevator system, the combination with an elevator car operable past a plurality of floors, each floor having a door assembly, of an electric motor operatively connected to each door assembly for opening it to permit entrance to the elevator car at the floor, circuit control means for connecting the motor individual to the door assembly at the floor where the elevator car is stopped to a source of electric power,-and protective circuit means disposed to be rendered effective during a predetermined portion of the travel of the elevator car from said floor in the event that said circuit control means remains in the operated condition after the elevator car leaves said floor for disconnecting said circuit control means from said power source, thereby preventing the subsequent energization of any of said motors.

3.. In an elevator system in which an elevator car is operated past a plurality of floors, each floor having a door assembly, in combination, an electric motor operatively connected to each door assembly for opening it to permit entrance to the elevator car at the floor, circuit control means individual to each floor and disposed to be operated on the stopping of the elevator car at the floor for connecting said motor at the floor to an electric power source, and means for preventing the subsequent connection of any of said motors to said power source in the event that any of said circuit control means remains in the operated condition after the elevator car leaves a floor where it has been stopped.

4. In an elevator system in which an elevator car is operated past a plurality of floors, each provided with an electric motor operated door assembly, in combination, circuit control means individual to each floor and disposed to be operated on the stopping of the elevator car at the floor for connecting the motor of said door assembly to a source of electric power to open said door assembly, and protective circuit means disposed to be rendered effective during a predetermined portion of the travel of the elevator car from a floor where it has stopped in the event that said circuit control means remains in the operated condition after the elevator car leaves said floor for disconnecting said circuit control means from said power source, thereby preventing the subsequent energization of any of said motors.

5. In an elevator system in which an elevator car is operated past a plurality of floors, each provided with an electric motor operated door assembly, in combination, circuit control means individual to each floor and disposed to be operated on the stopping of the elevator car at the floor for connecting the motor of said door assembly to a source of electric power to open said door assembly, a door protective relay disposed when energized to prevent the subsequent connection of any of said motors to said power source, and means for energizing said relay after the elevator car leaves a floor where it has stopped in the event that the circuit control means at said floor remains in the operated condition.

6. In an elevator system in which an elevator car is operated past a plurality of floors, each provided with an electric motor operated door assembly, in combination, circuit control means erated on the stopping of the elevator car at the floor for connecting the motor of said door assembly to a source of electric power to open said door assembly, a door protective relay disposed to prevent the subsequent connection of any of said motors to said power source, an operating winding for said relay, speed contact members disposed to be closed when the elevator car is operated above a predetermined speed, and speed relay contact members disposed to be closed when the elevator car is operated below a predetermined speed, said operating winding being connected in series circuit relation with said circuit control means, said speed contact members, and said speed relay contact members to said power source, whereby said winding is energized after the elevator car leaves said floor in the event that any of said circuit control means remains in the operated condition. y

7. In an elevator system in which an elevator car is operated past a plurality of floors, each prov vided with an electric motor operated door assembly, in combination, circuit control means individual to each floor and disposed to be operated on the stopping of the elevator car at the floor for connecting the motor of said door assembly to a source of electric power to open said door assembly, fuse means interposed in the conductors connecting the motors and said power source, a door protective relay disposed when energized to short circuit said conductors and blow said fuse means thereby preventing the subsequent connection of any of said motors to said power source, and means for energizing said relay after the elevator car leaves a floor where it has stopped in the event that the circuit control means at said floor remains in the operated condition.

8. In an elevator system in which an elevator car is operated past a plurality of floors, each provided with an electric motor operated door assembly, in combination, circuit control means individual to each floor and disposed to be operated on the stopping of the elevator car at the floor for connecting the motor of said door as sembly to a source of electric power to open said door assembly, fuse means interposed in the conductors connecting the motors and said power source, a door protective relay disposed when operated to short circuit said conductors and blow said fuse means thereby preventing the subsequent connection of any of said motors to said power source, an operating winding for said relay, speed contact members disp-osed to be closed when the elevator car is operated at a predetermined speed, and speed relay contact members disposed to be closed when the elevator car is op erated below a predetermined speed, said operating winding being connected in series circuit r lation with said circuit control means, said speed contact members, and said speed relay contact members to said power source, whereby said winding is energized after the elevator car leaves said floor in the event that any of said circuit control means remains in the operated condition.

9. In an elevator system in which an elevator car is operated past a plurality of floors, the elevator car being provided with a car door assembly and each floor with a floor door assembly, in combination, operating means individual to each door assembly, control means for energizing the operating means individual to the floor door assembly at the floor where the car is stopped simultaneously with the energization of the operating means for the car door assembly, and means for preventing the energization of any of said operating means in the event that any of said control means individual to the floor door assemblies remains in the operated position after the elevator car leaves said floor.

10. In an elevator system in which an elevator car is operated past a plurality of floors, the elevator car being provided with a car door assembly and each floor with a floor door assembly, in combination, an electric motor operatively connected to each door assembly, circuit control means individual to each floor and disposed to be operated on the stopping of the elevator car at the floor to permit the connection of the motor individual to the floor door assembly to a source of electric power simultaneously with the connection of the motor individual to the car door assembly to said source, and means for preventing the subsequent connection of any of said motors to said power source in the event that any of said circuit control means remains in the operated condition after the elevator car leaves a floor where it has been stopped.

11. In an elevator system in which an elevator car is operated past a plurality of floors, the elevator car and each floor being provided with an electric motor operated door assembly, in combination, circuit control means individual to each floor and disposed to be operated on the stoppin of the elevator car at the floor to permit the connection of the motor individual to the floor door assembly to a source of electric power simultaneously with the connection of the motor individual to the car door assembly to said source, and protective circuit means disposed to be rendered effective during a predetermined portion of the travel of the elevator car from a floor where it has stopped in the event that said circuit control means remains in the operated condition after the elevator car leaves said floor for disconnecting said circuit control means from said power source, thereby preventing the subsequent energization of any of said motors.

12. In an elevator system in which an elevator car is operated past a plurality of floors, the elevator car and each floor being provided with an electric motor operated door assembly, in combination, circuit control means individual to each fioor and disposed to be operated on the stopping of the elevator car at the floor to permit the connection of the motor individual to the floor door assembly to a source of electric power simultaneously with the connection of the motor individual to the car door assembly to said source, a door protective relay disposed when energized to prevent the subsequent connection of any of said motors to said power source, and means for energizing said relay after the elevator car leaves a floor where it has stopped in the event that the circuit control means at said floor remains in the operated condition.

13. In an elevator system in which an elevator car is operated past a plurality of floors, each floor having a door assembly, in combination, operating means individual to each door assembly and disposed to open it to permit entrance to the elevator car at the floor, cont-r01 means for said operating means, and means responsive to faulty operation of the control means for the operating means at any floor and to operation of the car for a stop for preventing operation of the operating means individual to the door assembly at any floor.

14. In an elevator system for operating a car serving a plurality of floors each of which is provided with a door, the combination with an operating means individual to each door and control means for effecting operation of the door operating means at any floor when the car stops thereat, of means responsive to operation of the car in making a stop at a door for preventing the control means from effecting operation of the door operating means at any door except the door for which the car is making the stop HAROLD W. WILLIAMS. 

